1. Technical Field
The present invention relates in general to an improved data access and storage device, and in particular to an improved direct access and storage device that utilizes multiple actuators. Still more particularly, the present invention relates to a direct access and storage device with multiple actuators that may be operated independently, in parallel, or selectively actuated by the user.
2. Description of the Prior Art
Generally, a data access and storage system consists of one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. Disks are rigid platters that are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, two or three disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
The only other moving part within a typical HDD is the head stack assembly. Within most HDDs, one magnetic read/write head or slider is associated with each side of each platter and flies just above or below the platter""s surface. Each read/write head is mounted on a suspension to form a head gimbal assembly (HGA) . The HGA is then attached to a semi-rigid arm apparatus that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single armature unit.
Each read/write head scans the surface of a disk during a xe2x80x9creadxe2x80x9d or xe2x80x9cwritexe2x80x9d operation. The head and arm assembly is moved utilizing an actuator that is often a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the disk spindle is also mounted. The base casting is in turn mounted to a frame via a compliant suspension. When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop directly over the desired track. The data on the spinning media is then read via a magnetic read sensor (typically magnetoresistive) on the read-write head.
As the storage capacity of DASDs continues to increase, a single disk drive enclosure may encounter many different kinds of applications. For example, a drive may be required to perform a very high throughput sequential operation, or a very high input/output rate random operation. Although there is no present manner of optimizing performance based upon any particular access characteristics, U.S. Pat. No. 5,293,282, discloses a disk drive with multiple actuators. The multiple actuators have multiple heads that read data from and write data to all tracks on the surfaces of the disks. The positioning of each head by respective actuators is controlled by embedded servo information recorded in the data tracks. Utilizing two actuators provides increased data transfer rates and reduced access times with respect to the access times provided by disk drives having a single actuator. However, that disk drive has no mechanism for optimizing the drive""s performance for the different types of access characteristics. In order to increase performance while handling the diversity of operations required of modern disk drives, an improved system and method for efficiently utilizing the drives is needed.
A hard disk drive for a computer system has at least two actuators for reading data from or writing data to the disks. The actuators may be configured to support the different methods of data access required of them. For example, if large quantities of sequential data are performed, one operation uses both actuators to increase throughput. However, if mostly random operations are to be performed, then independent usage of the actuators is preferred. These two methods of usage can be supported simultaneously, and can even be dictated by the user. The tracking format of the actuators can be configured such that the next logical track is physically located under a head on a different actuator to improve sequential operation. The actuators also may be utilized in a dual-channel configuration so that data can be written to both actuators at the same time, or read back at the same time to improve throughput. In addition, either of these go configurations can be selected on a transfer-by-transfer basis by the user.
The foregoing and other objects and advantages of the present invention will be apparent to those skilled in the art, in view of the following detailed description of the preferred embodiment of the present invention, taken in conjunction with the appended claims and the accompanying drawings.